I've been having some trouble tuning my FD and I thought I would ask around for some advice. I have a large street port, 60-1 turbo, custom manifold, etc.. and I'm using a Fueltronics Wideband A/F meter. I dont have an EGT gauge at this time. When I take my car out for some highway runs, it reads 10.0:1 across the board on the first pull. I take it for a second pull and the readings go up a little (leaner) to approx 11:1. On the third run they go up to 12 and 13:1. Basically the the wideband is getting heat soaked and overheated after only a few runs. It is currently just clipped to the tailpipe. When I mounted it at the midpipe it read very lean conditions on the first two runs which is why it's on the tailpipe right now. I am assuming my EGT's are too high so I am looking for a way to lower them. I could slowly take out fuel, but I'm not sure if the WB is overheated or giving me true lean readings. I have the timing set to 10 degrees under boost and I am tuning with a haltech E6K. I'm not exactly sure what the split is off the top of my head, but it is around 12 degrees under boost. Is there anything else I can do with the tuning to lower my EGTs or is there another problem I am missing? I plan to try a different WB meter and get an EGT gauge in the future but I'd like to get this taken care of sooner than later so I can feel safe driving my car under boost.

Josh

 

if your afr's aren't consistent from one run to the next, there's a problem. since it's clipped onto the tailpipe, i wanna rule out heat soak. mine is about a foot after my turbo and i never have problems with that.

maybe you're getting dilution from being so close to the end of the pipe?

 

How much do the EGT's vary? If they dont change that much I would suspect something is suspect with the WB unit/sensor.

Fish

 

unless your'e in 5th and give it a really long run, the egt doesn't react fast enough to tell.

 

Try using 3rd or 4th then.

Fish

 

3rd or 4th won't give the egt enough time to respond.

 

i don't have an EGT guage, so I don't know how much it varies. I can't think of any other logical explanation as to why the AF readings gradually increase from one run to the next except for heat soak. The Wide Band reads fine in all my other cars (daily drivers), so I know the Wide Band is not faulty. Any other ideas?

 

Uh, ok.


-Ted

 

what kind of egt do you use? mine's slow

 

I use only GReddy EGT's.
I've also used Blitz, A'PEXi, and Omori EGT's, and their reaction was good enough for me to use.


-Ted

 

I am using, and have been using an SPA digital gauge, and never had any problems with it.

Fish

 

i've got that apexi nite-light gauge. it's got some nice features like the peak/hold, and 30 second playback, but it reacts really slow.

wonder if i just need a new probe? but i haven't seen any egt's that react all THAT fast..

 

you probably have this covered but...

the fuel correction tables re temperature are pretty crude. might it be that your first runs have been at less than normal water ( around 84 cel ) temp? that would generally throw off your afrs.

your timing, btw, is very conservative... 15 degrees w 14 split under boost works pretty well w your setup.

good luck,

howard coleman

 

I try to keep tuning conservative to prevent these types of problems. I think the best thing to do it just buy an EGT gauge and go from there.

 

hey ted, do you like the probe in the manifold or after the turbo?

 

I prefer the EGT probe in the turbo exhaust manifold.
It does react a split second faster close to the exhaust ports.


-Ted

 

how often do yours wear out?

 

I've had it installed at least 5 years ago, and it doesn't show any signs of dying anytime soon.


-Ted

 

interesting. what i've heard is they'll wear out really quick if they're that close to the port exit.

non-related----but have you ever checked the temp difference between the manifold and right after the turbo? i was told and stick to low-mid 700's (about 6" after the turbo) is safe. what do you usually tune egt's for?

 

I used to use a GReddy 52mm EGT gauge right after the turbo.
I have since switched to a GReddy 60mm P/H gauge in the turbo exhaust manifold.
Both set-up's were on (basically) a stock turbo + ported motor on my 1987 FC turbo.

Boost at 14psi max.
EGT probe in downpipe
720C - 740C WOT (verified with a Horiba Lambda wide-band)
780C cruising closed-loop

EGT probe in turbo exhaust manifold
760C - 780C WOT
820C cruising closed-loop

Keep in mind, this is using a stock FC3S turbo.
Aftermarket turbo tend to run higher EGT's (in my experience), so there numbers would be pretty cold for anything aftermarket.


-Ted

 

gotcha.
i thought there was more like a 150+ difference between the manifold and after the turbo but i guess ya learn something new everyday huh?

thanks for the info.

now as far as reaction time is concerned, i'll see what it's like when i get the new probe.

 

I was able to get on a dyno yesterday with a wideband hookup. Turns out the car was very lean. Honestly, I'm surprised my motor didn't blow on the first run (big thumbs up for RA seals!!). I did about 6 runs, adjusting the fuel a little on each run until I got it in the 10:1 to 11:1 range. I dont have all the dyno sheets, but they guy at the shop printed out the first run for me. All runs were in between 360 to 365 HP. Torque was in the 280 range for all the runs. Surprisingly the power curves didnt change much from the first to the last run and I probably added about 15-20 % of fuel between the first and last runs.
Interestingly enough, my boost creep began to go away as I was adding fuel
All of my runs were in the 12-13 psi range. I was running off of a 12 psi WG spring (no boost controller) and I had a little creep in the mid to upper RPM range.
Let me get this graph hosted then will post it.

 

Here's the chart:

 

a/f is all over the place. that was the first run right?
what kind of turbo are you using?

 

That was the first run and the car was untuned (new motor, new ports, etc..). I ran what I thought would be a safe "base" map but turns out it was not even close to being safe. The car is tuned pretty safe right now as I explained in my earlier post. The turbo is a 60-1 with 1.0 turbine.